Essential infrastructure: how OpenSAFELY revolutionised health data analysis during the COVID-19 pandemic

In the early weeks of the COVID-19 pandemic, researchers knew that NHS GP records held vital clues about who was most at risk from COVID-19. However, privacy concerns had long prevented researchers from accessing whole-population data for large-scale analysis.

OpenSAFELY solved that problem.

Rather than allowing researchers to make copies of raw data from GP records, OpenSAFELY was designed to leave the data where it was already stored – taking the research code to the data, then bringing back aggregated results in the form of tables and graphs. Most importantly, for patient confidentiality, researchers only get to see insights; they never get unconstrained access to the raw data.

While OpenSAFELY was designed as a novel solution to an unprecedented global crisis, it has since been recognised in the UK Covid-19 inquiry as essential to the UK’s pandemic response, highlighting the potential for secure, large-scale health data analysis to save lives.

A landmark recognition: OpenSAFELY’s mentions in the UK Covid-19 inquiry

In April 2026, OpenSAFELY was named in Module 4 of the UK Covid-19 inquiry as one of several systems – including the NHS England Vaccine Equalities Tool and ONS data – that contributed to the UK’s vaccines and therapeutics infrastructure during the pandemic.

The report highlighted OpenSAFELY’s role in two critical areas:

1. Monitoring vaccine uptake disparities: From the very start of the roll-out in January 2021, OpenSAFELY was able to show gaps in vaccine coverage, demonstrating that a person’s ethnic background or level of poverty affected their likelihood of getting vaccinated.
2. Performing safety analyses: the Medicines & Healthcare Products Regulatory Agency (MHRA) and Clinical Practice Research Datalink (CPRD) used OpenSAFELY to analyse millions of GP records – quickly, safely, and securely – to make sure that vaccines were safe and effective.

This recognition speaks to the scale of what OpenSAFELY achieved during the pandemic, and to the transformative potential of secure, large-scale data analysis to shape future health policy and research.

OpenSAFELY’s real-world impact: research, collaboration, and policy

Since its launch in 2020, OpenSAFELY has had an enormous impact on clinical and health policy in England.

Beyond Nature’s study on the factors associated with COVID-19-related deaths – cited in 71 different policy documents with over 380 news mentions – OpenSAFELY directly informed decision-making at the Scientific Advisory Group for Emergencies (SAGE) and the Joint Committee on Vaccination and Immunisation (JCVI), as well as several specialised policy documents relating to:

• A&E attendance in England
• Learning disabilities
• COPD and Asthma
• HIV infection

OpenSAFELY also enabled major collaborative studies with researchers from the University of Bristol, the London School of Hygiene & Tropical Medicine (LSHTM), Harvard University and other leading research institutions to evaluate the real-world effectiveness and safety of COVID-19 vaccines at unprecedented scale.

Just 9 days after the first patient was vaccinated, we created live NHS vaccination dashboards to track uptake across different communities and vulnerable patient groups, providing critical information about lower vaccination rates among Black communities, people with severe mental illness, and those with learning disabilities, helping the NHS target outreach efforts.

We were able to compare vaccines head-to-head, monitor how protection changed over time, and study outcomes in vulnerable patient groups often excluded from clinical trials. For example, we found that Astra-Zeneca performed as well as Pfizer (BMJ; 10.1136/bmj-2021-068946, 10.1136/bmj-2022-072808) in health and social care workers, and that mixed-brand booster programmes could provide stronger protection for people with chronic kidney disease (Lancet; 10.1016/j.lanepe.2023.100636).

Together, these studies – and many others – showed how OpenSAFELY turned secure NHS data into near real-time evidence, shaping national vaccine policy, improving protection for vulnerable groups, and helping the NHS deliver a more effective and equitable pandemic response.

What’s next for OpenSAFELY?

From the beginning, we’ve been determined to improve people’s lives through better use of data – without compromising people’s privacy. While OpenSAFELY was born out of an unprecedented global crisis, its long-term potential extends far beyond the pandemic.

Expanding into broader areas of health research and analysis – including NHS Talking Therapy outcomes and education – OpenSAFELY offers a model for what becomes possible when technical innovation and rigorous privacy protections are built together – and equally prioritised – from the start.

To learn more about our work with big data, visit the Bennett Institute’s website, follow the Bennett Institute on LinkedIn and @bennettoxford.bsky.social (BlueSky), and sign up to receive notifications of the latest blog posts and newsletter updates.